We present two millisecond pulsar discoveries from the PALFA survey of the Galactic plane with the Arecibo telescope. PSR J1955+2527 is an isolated pulsar with a period of 4.87 ms, and PSR J1949+3106 has a period of 13.14 ms and is in a 1.9 day binary system with a massive companion. Their timing solutions, based on 4 years of timing measurements with the Arecibo, Green Bank, Nançay, and Jodrell Bank telescopes, allow precise determination of spin and astrometric parameters, including precise determinations of their proper motions. For PSR J1949+3106, we can clearly detect the Shapiro delay. From this we measure the pulsar mass to be 1.47+0.43 – 0.31 M ☉, the companion mass to be 0.85+0.14 – 0.11 M ☉, and the orbital inclination to be i = 79.9–1.9 + 1.6 deg, where uncertainties correspond to ±1σ confidence levels. With continued timing, we expect to also be able to detect the advance of periastron for the J1949+3106 system. This effect, combined with the Shapiro delay, will eventually provide very precise mass measurements for this system and a test of general relativity.

The authors acknowledge support from the NSF grant AST-0807151 to Cornell University, the NSERC, the Canada Foundation for Innovation, CANARIE, the European Research Council for the ERC Starting Grant BEACON under contract no. 279702, the Veni Fellow of the Netherlands Foundation for Scientific Research (NWO), the Max Planck Society, an NSERC PGS scholarship, and an IMPRS fellowship.